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<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
  </head>
  <body>
    <div class="father">
      父元素
      <div class="son">子元素</div>
      <div>
        <div class="grandson"> 
          孙子元素
      </div>
    </div>
  </body>
</html>
<style>
  .father > .son {
    color: red;
  }
</style>
<script></script>
